Seeing as they design for 50c flow temperature I would think that nothing is too frequent.
My 9kW used to defrost once every 23 minutes at its peak when running at 42c in icing conditions.
It was awful.
Does it matter whether you have the emitters set to radiators vs fan coils Vs underfloor heating?
If emitters were fan coils I’d imagine it would need to use dhw for defrosting
I have emitters set to underfloor to unlock the full range of overshoot and deltaT. I’m currently running an overshoot of 3 and DT of 5. The octopus default is to set emitters to fancoil when using radiators.
Experimenting with setting to fancoil emitters now. It restricts overshoot to 1 degree which is annoying as in the shoulder months a 3 degree overshoot stopped a cycle that often happened about 20mins after starting up (probably due to the heat from the buffer working its way through the system). Tonight should be cold enough for a defrost - we shall see!
I think the overshoot limitation on fan coils was fixed with a software update? There’s another thread around here somewhere… @KnightPhoenix or @matt-drummer might remember
Overshoot was available in fan coils and ufh on my heat pump between 1c and 4c.
It was fixed at 1c on radiators.
I had a firmware update on the heat pump itself in May 2024 and it made the full overshoot adjustment available between 1c and 4c in all three modes.
Daikin had to do this.
I like to run on radiators with a fixed dT of 10c and the lack of full overshoot was an issue.
Running using radiators has always given me the best efficiency with both the 9kW and 8kW.
A lower dT and varying flow rate has never worked the best for me, I like the flow rate at the minimum at all times other than the initial start of a heating cycle. Even that I restrict the flow rate to the minimum possible.
2 Likes
Did you contact Daikin direct for that firmware update or go via Octopus?
Always through Octopus
2 Likes
I had noticed this from time to time last year, and just noticed it happen as I was by chance, close by the 3 way ESBE valve, and could hear it move across yet I knew the hot water schedule was not set until tonight (set by our Mixergy cyclinder controller).
December 7th 2024 at approx 13:08
Has anyone figured out why this happens occasionally, and has anyone had a firmware update that resolves it?
Nothing yet, still waiting on Octopus to respond.
1 Like
Your flow temps are pretty low at the time it happened so I suspect that may be a factor.
2 Likes
For my system, think it uses the tank for the defrost when it is one of the periodic (every 6 hours or so of runtime?) “defrosts”, not a true low-temperature defrost.
It may also require a certain temperature in the tank, but I’m less sure of that.
Still, I’ve never seen a noticeable drop in tank temperature due to this
2 Likes
12 hours of compressor being on afaik looking at my summertime defrosts
1 Like
Yep, my system (EDLA11) has a “defrost” every 6 hours on the dot regardless if needed.
I have in the past seen tank temperature and State of Charge drop (I have a Mixergy tank so have a lot of data to show this) when the “defrost” switches source to DHW
I think we can put that hypothesis to bed!
Again, the “6 hour countdown timer based false defrost” switched to DHW mode, and weirdly shuts off for ~5min afterwards before coming back to start Space Heating again.
And for context, had been running for a fair while after being off from 05:30 to 11:30, and actually running “harder” than normal/needed from ~3pm in preparation for the Octopus Saving Session this evening at 6-7pm
I can confirm this behavior of Samsung HP but it is not doing only at defrost cycles in case you have monoblok. It’s doing it also when the HP needs to increase return temperature e.b. in case there is cold outside around 0C to prevent water freezing outdoor unit.
Recently I’ve installed 280L DHW tank and noticed this behavior. From midnight to 6.a.m I usually turn of the pump with termostat by lowering target temperature by 2C. It usually lasts until morning without single start of a compressor. Before I had a DHW tank you may see that the pump simply run pump for around 5 minutes without starting compressor. What happened was that flow temperature decreases slightly and return increased which ensured the water will not freeze. The flow temperature drop is marginal.
What I’ve noticed with DHW tank installed is simply stupid. When the pump wants to increase return temp to prevent freezing for some unknown reason it explicitly switch 3-way valve to DHW and steal water from a tank !! Why. In my opinion this is not necessary at all. Without DHW tank it didn’t have such possibility and only decrease water in radiators slightly.
With DHW installed this happening. During a night it was 1.6C on average and the pump stole heat from the tank 4x (each run of the pump exactly 6 minutes) until it dropped to 40C and reheat to 50 started. In the morning it took 6.4C from the water tank! The return temperature still dropped by 10C so not sure what is this good for. What is the benefit in comparison with scenario without DHW tank I’ve posted earlier.
It’s pretty strange it is doing this with DHW installed. It’s even not a defrost cycle. I’m yet to observe full defrost cycle with DHW installed but I’m trying to understand this behavior. I would rather keep it as it was to use circulating water from space heating circuit than stealing heat from DHW tank. It’s not made for that lol.
1 Like